The field of the invention pertains to fixtures that can be adjusted or reassembled to provide more than one cutting function for motor driven cutting tools. In particular, the fixtures may include the motor drive unit for a variety of cutting functions as an integral part of the fixture assembly. The "Shopsmith" brand mutiple use tool exemplifies such a tool wherein the framework adjusts to a variety of positions and the cutting heads may be interchangeably attached to the motor driven unit.
The motor drive unit may, alternatively, be a separate entity from the fixture such as a common electric hand drill or a "Dremel" brand high speed electric grinder. Although the large multiple use machines tend to provide integral motor drive units and the small multiple use machines to use common small drills or grinders there are exceptions such as the "Unimat" brand combination metal lathe and vertical mill.
U.S. Pat. No. 2,768,663 and U.S. Pat. No. 2,888,965 both disclose multiple use fixtures for a common portable electric hand drill. The most common fixture adaptations are to a lathe and a drill press with other options including a grinder, router and plane. U.S. Pat. No. 2,255,541 discloses fixtures to convert a "Dremel" brand grinder into a shaper and a router and U.S. Pat. No. 2,672,898 illustrates a fixture for edge dressing and profiling with a small electric grinder.
U.S. Pat. No. 3,288,183 and U.S. Pat. No. 3,179,136 disclose fixtures to convert portable electric hand drills to portable routers and other uses. Similarly U.S. Pat. No. 4,057,358 and U.S. Pat. No. 4,235,565 disclose fixtures to precisely locate a portable electric drill for accurately locating dowel joints. U.S. Pat. No. 2,822,836 discloses the conversion of a portable electric drill into a table saw or portable hand saw. The common factor among all of the disclosures is the requirement for several very specialized and expensive parts in each of the fixture assemblies. Such expensive parts, in particular, special machined castings, substantially increase the cost to manufacture the fixtures and thereby limit their use. With a view toward drastically decreasing and substantially eliminating the number of specialized parts in a multiple use fixture assembly for a cutting tool and also providing a different combination of uses, applicant has invented the fixture assembly combination disclosed below.